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Chapter 6: Omnia-3net/drm
This chapter presents important installation and operation information specific to the Omnia-3net/drm. A block
diagram for the Omnia-3net/drm is shown below. An Omnia-3net/drm Parameters Worksheet is included at the
end of this chapter. Use it as a master sheet for photocopying so that the parameter settings for any custom
presets can be recorded. Presets can also be saved to your computer and printed using the Omnia-3 Remote
Control software.
Omnia-3net/drm Connections
The Omnia-3net/drm is designed to provide audio processing for Webcasting, DAB and similar applications.
The unit provides full maximum 20 kHz bandwidth and audio processes which are optimized for a variety of
coding algorithms. Because of the company's extensive experience with MP3 and other codec technologies, the
Omnia-3net/drm is designed to maximize the sound quality of networked audio, even at low bit-rate settings.
When the unit is connected to a professional-grade real-time encoder, the AES/EBU outputs will generally be
used to eliminate conversion steps. The inputs can be from either analog or digital (AES/EBU) sources.
The analog outputs can also be used to connect to the encoding equipment. If the encoder is a PC card, care
should be exercised to prevent ground loops and other connection problems. In the case where the PC card
audio inputs are unbalanced (typically an RCA or mini-phone jack is used), connect the + signal output (pin 2
on the XLR connector) to the tip of the unbalanced plug. Connect the shield on the unbalanced plug to pin 1
(Ground) on the XLR connector. In this application you do not connect pin 3 of the XLR (the - output).
The factory processing presets have been optimized for use with coded audio. They should be used as a starting
point to optimize the audio for your exact coding requirements. For more information on audio processing for
the Internet, refer to the white paper on Audio Processing for DAB and the Internet found on the Omnia web
page:
http://www.omniaaudio.com/
Adjustments to the processing preset parameters are covered in Chapter 7, Editing Presets.
Omnia-3net/drm System Adjustments
The system parameters pertaining only to the Omnia-3net/drm are found under the Input & Output menu.
Input & Output
LPF Freq(uency)
This is a key control for matching the audio bandwidth of the processed audio to bitrate of the following codec.
Proper bandwidth will ensure minimal side effects and aliasing distortion products from the codec process.
Settings are: 4, 6, 8, 10, 13, 16 and 22 kHz. These are the frequencies at which the filter reaches full (at least
100dB) attenuation. A frequency at or below half the sampling frequency of the encoder should be selected.
